Android™

Create PEM-encoded PKCS#7 Detached Signature

See more Digital Signatures Examples

Demonstrates how to create a PKCS7 PEM-encoded object containing a detached signature. Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkCert cert = new CkCert();

    // Load the cert and private key.
    success = cert.LoadPfxFile("qa_data/pfx/myCertAndKey.p12","password");
    if (success != true) {
        Log.i(TAG, cert.lastErrorText());
        return;
        }

    CkCrypt2 crypt = new CkCrypt2();

    success = crypt.SetSigningCert(cert);
    if (success != true) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    // Use SHA-256
    crypt.put_HashAlgorithm("sha256");

    // Hash the utf-8 byte representation of the string
    crypt.put_Charset("utf-8");

    // Return the result in base64
    crypt.put_EncodingMode("base64Mime");

    // Sign some text to create a detached signature (i.e. a signature that does not include the signed data)
    String textToSign = "This is the text to be hashed and signed.";
    String sigBase64 = crypt.signStringENC(textToSign);
    if (crypt.get_LastMethodSuccess() != true) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    Log.i(TAG, sigBase64);

    // The result:

    // MIIWbgYJKoZIhvcNAQcCoIIWXzCCFlsCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
    // ghMXMIIFuzCCA6OgAwIBAgIIVwoRl0LE48wwDQYJKoZIhvcNAQELBQAwazELMAkGA1UEBhMCSVQx
    // ...
    // ...

    // If we want it in PEM format with just LF line-endings:
    CkStringBuilder sb = new CkStringBuilder();
    // Just LF line endings, not CRLF.
    boolean crlf = false;
    sb.AppendLine("-----BEGIN PKCS7-----",crlf);
    sb.Append(sigBase64);
    sb.AppendLine("-----END PKCS7-----",crlf);
    sb.ToLF();

    // Save to a file.
    sb.WriteFile("c:/temp/qa_output/sig.pem","utf-8",false);

    // Examine..
    Log.i(TAG, sb.getAsString());

    // Result is:

    // -----BEGIN PKCS7-----
    // MIIWbgYJKoZIhvcNAQcCoIIWXzCCFlsCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
    // ghMXMIIFuzCCA6OgAwIBAgIIVwoRl0LE48wwDQYJKoZIhvcNAQELBQAwazELMAkGA1UEBhMCSVQx
    // DjAMBgNVBAcMBU1pbGFuMSMwIQYDVQQKDBpBY3RhbGlzIFMucC5BLi8wMzM1ODUyMDk2NzEnMCUG
    // A1UEAwweQWN0YWxpcyBBdXRoZW50aWNhdGlvbiBSb290IENBMB4XDTExMDkyMjExMjIwMloXDTMw
    // MDkyMjExMjIwMlowazELMAkGA1UEBhMCSVQxDjAMBgNVBAcMBU1pbGFuMSMwIQYDVQQKDBpBY3Rh
    // bGlzIFMucC5BLi8wMzM1ODUyMDk2NzEnMCUGA1UEAwweQWN0YWxpcyBBdXRoZW50aWNhdGlvbiBS
    // b290IENBMIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAp8bEpSmkLO/lGMWwUKNvUTuf
    // ClrJwkg4CsIcoBh/kbWHuUA/3R1oHwiD1S0eiKD4j1aPbZkCkpAW1V8IbInX4ay8IMKx4INRimlN
    // AJZaby/ARH6jDuSRzVju3PvHHkVH3Se5CAGfpiEd9UEtL0z9KK3giq0itFZljoZUj5NDKd45Rnij
    // MCO6zfB9E1fAXdKDa0hMxKufgFpbOr3JpyI/gCczWw63igxdBzcIy2zSekciRDXFzMwujt0q7bd9
    // ...
    // ...
    // -----END PKCS7-----

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}